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FM Communication Basic Concepts of FM Communications

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FM Communication Basic Concepts of FM Communications FM Communication basic concepts of FM Communications PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information. PDF generated at: Thu, 23 Jun 2011 04:26:27 UTC Contents Articles Fundamentals 11 TTeelleeccoommmmuunniiccaattiioonn 11 EElleeccttrroommaaggnneettiiccrraa ddiiaattiioonn 1155 EElleeccttrroommaaggnneettiicciinn dduuccttiioonn 2233 Frequency 2255 FFrreeqquueennccyyssyynntthheessiizzeer r 2255 FFrreeqquueennccyy mmii xxeerr 2299 VVeerryyhhiiggh hffrreeqquueennccy y 3322 UUllttrraahhiiggh hffrreeqquueennccy y 3377 SSuuppeerrhhiiggh hffrreeqquueennccy y 4499 EExxttrreemmeellyyhhiiggh hffrreeqquueennccy y 5500 Modulation 5544 MMoodduullaattiioonn 5544 Transmitter 6600 TTrraannssmmiitttteerr 6600 Antenna 6677 AAnntteennnnaa ((rraa ddiioo)) 6677 Reciever 8877 RReecceeiivveerr ((rraa ddiioo)) 8877 TTuunneeddrr aaddiiooff rreeqquueennccyyrr eecceeiivveerr 9933 Radar 9966 RRaaddaarr 9966 Applications 114 TTrraannssiissttoorr rraa ddiioo 111144 WWaallkkiiee--ttaallkkiiee 111199 Extra Knowledge 127 NNooiissee((eelleeccttrroonniiccss) ) 112277 IInndduuccttiioonnpp llaassmmaatt eecchhnnoollooggyy 112299 References AArrttiicclleeSS oouurrcceessaa nnddCC oonnttrriibbuuttoorrss 113355 IImmaaggeeSS oouurrcceess,,LL iicceennsseessaa nnddCC oonnttrriibbuuttoorrss 113388 Article Licenses LLiicceennssee 114411 11 Fundamentals Telecommunication Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded drumbeats, lung-blown horns, or sent by loud whistles, for example. In the modern age of electricity and electronics, telecommunications now also includes the use of electrical devices such as telegraphs, telephones, and teletypes, the use of radio and microwave communications, as well as ffiberiber optics and their associated electronics, plus the use of the orbiting satellites and the Internet. A revolution in wireless telecommunications began in the first decade A Gower telephone, at the Musée des Arts et of the 20th century, with Guglielmo Marconi winning the Nobel Prize Métiers in Paris in Physics in 1909 for his pioneering developments in wireless radio communications. Other highly notable pioneering inventors and developers in the field of electrical and electronic telecommunications include Charles Wheatstone and Samuel Morse (telegraph), Alexander Graham Bell (telephone), Nikola Tesla, Edwin Armstrong, and Lee de Forest (radio), as well as John Logie Baird and Philo Farnsworth (television). Telecommunications play an important role in the world economy and the worldwide telecommunication industry's revenue was estimated to be $3.85 trillion in 2008.[1][1] The service revenue of the global telecommunications industry was estimated to be $1.7 trillion in 2008, and is expected to touch $2.7 trillion by 2013.[1][1] History Ancient systems Greek hydraulic semaphore systems were used as early as the 4th century BC. The hydraulic semaphores, which worked with water filled vessels and visual signals, functioned as optical telegraphs. However, they could only utilize a very limited range of pre-determined messages, and as with all such optical telegraphs could only be deployed during good visibility conditions.[2][2] During the Middle Ages, chains of beacons were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon iinn advance. One notable instance of their uusese was duringduring the Spanish Armada, when a beacon chain relayed a signal from Plymouth to London that signaled the arrival of the Spanish warships.[3][3] Telecommunication 22 Systems since the Middle Ages In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system (or semaphore line) between Lille and Paris.[4][4] However semaphore systems suffered from the need for skilled operators and the expensive towers at intervals of 10 – – 30 kilometers (6(6 – – 20 mi). As a result of competition from the electrical telegraph, Europe's last commercial semaphore line in Sweden was abandoned in [5][5] 1880. The telegraph and telephone The first commercial electrical telegraph was constructed by Sir Charles Wheatstone and Sir William Fothergill Cooke, and its use began on April 9, 1839. Both Wheatstone and Cooke viewed their device as "an improvement to the [already-existing, so-called] electromagnetic telegraph" not as a new device.[6][6] The businessman Samuel F.B. Morse and the physicist Joseph Henry A replica of one of Chappe's semaphore towers in of the United States developed their own, simpler version of the Nalbach electrical telegraph, independently. Morse successfully demonstrated this system on September 2, 1837. Morse's most important technical contribution to this telegraph was the rather simple and highly efficient Morse Code, which was an important advance over Wheatstone's complicated and significantly more expensive telegraph system. The communications efficiency of the Morse Code anticipated that of the Huffman code in digital communications by over 100 years, but Morse and his associate Alfred Vail developed the code purely empirically, unlike Huffman, who gave a detailed theoretical explanation of how his method worked. The first permanent transatlantic telegraph cable was successfully completed on 27 July 1866, allowing transatlantic electrical communication for the first time.[7][7] An earlier transatlantic cable had operated for a few months in 1859, and among other things, it carried messages of greeting back and forth between President James Buchanan of the United States and Queen Victoria of the United Kingdom. However, that transatlantic cable failed soon, and the project to lay a replacement line was delayed for five years by the American Civil War. Also, these transatlantic cables would have been completely incapable of carrying telephone calls even had the telephone already been invented. The first transatlantic telephone cable (which incorporated hundreds of electronic amplifiers) was not operational until 1956.[8][8] The conventional telephone now in use worldwide was first patented by Alexander Graham Bell in March 1876.[9][9] That first patent by Bell was the master patent of the telephone, from which all other patents for electric telephone devices and features flowed. Credit for the invention of the electric telephone has been frequently disputed, and new controversies over the issue have arisen from time-to-time. As with other great inventions such as radio, television, the light bulb, and the digital computer, there were several inventors who did pioneering experimental work on voice transmission over a wire, and then they improved on each other's ideas. However, the key innovators were Alexander Graham Bell and Gardiner Greene Hubbard, who created the first telephone company, the Bell Telephone Company in the United States, which later evolved into American Telephone & Telegraph (AT&T). The first commercial telephone services were set up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven, Connecticut, and London, England.[10] [11] Telecommunication 33 Radio and television In 1832, James Lindsay gave a classroom demonstration of wireless telegraphy via conductive water to his students. By 1854, he was able to demonstrate a transmission across the Firth of Tay from Dundee, Scotland, to WWoodhaven,oodhaven, a distance of about two miles (3 km), again using watwaterer as the transmission medium.[12] In December 1901, Guglielmo Marconi established wireless communication between St. John's, Newfoundland and Poldhu, Cornwall (England), [13] earning him the Nobel Prize in Physics for 1909, one which he shared with Karl Braun. However small-scale radio communication had already been demonstrated in 1893 by Nikola Tesla in a presentation before the National Electric Light Association.[14] On March 25, 1925, John Logie Baird of Scotland was able to demonstrate the transmission of moving pictures at the Selfridge's department store in London, England. Baird's system relied upon the fast-rotating Nipkow disk, and thus it became known as the mechanical television. It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning September 30, 1929.[15] However, for most of the 20th century, television systems were designed around the cathode ray tube, invented by Karl Braun. The first version of such an electronic television to show promise was produced by Philo Farnsworth of the United States, and it was demonstrated to his family in Idaho on September 7, 1927.[16] Computer networks and the Internet On 11 September 1940, George Stibitz was able to transmit problems using teletype to his Complex Number Calculator in New York and receive the computed results back at Dartmouth College in New Hampshire.[17] This configuration of a centralized computer or mainframe computer with remote "dumb terminals" remained popular throughout the 1950s and into the 60's. However, it was not until the 1960s that researchers started to investigate packet switching — — a technology that allows chunks of data to be sent between different computers without first passing through a centralized mainframe. A four-node network emerged on December
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